The present invention relates to manual self-inking stamping devices of the type having a self-inking stamp pad for impressing any suitable surface with a printed message, design or the like. Typical prior art devices utilize a base member for receiving therein the stamp pad, a depressable handle affixed to the stamp pad for effecting contact of the stamp pad with the surface to be stamped, and biasing means for normally urging the stamp pad upwardly within the base means. The handle may be depressed against the urging of the biasing means to cause the stamp pad to contact the surface to be stamped. While these devices provide generally satisfactory printing results, they suffer from the disadvantage that the stamping pressure exerted in depressing the handle cannot be uniformly regulated. When the self-inking stamp pad is relatively new, and therefore has an ample supply of ink retained therein, only a light depressing force on the handle is necessary to effect satisfactory printing. However, when the stamp pad has been in use for a considerable length of time, a relatively greater depressing force must be exerted on the handle to achieve comparable printing. The accurate regulation of the depressing force necessary to achieve uniform printing results throughout the useful life of the stamp pad is not possible with such prior art stamping devices.
Other prior art stamping devices have employed various means allowing selective adjustment of the distance which the handle may be depressed thereby facilitating regulation of the stamping pressure exertable upon depression of the handle. One such prior art device employs a two-part bushing disposed below the handle of the stamping device and about a shaft extending from the handle to the stamp pad to act as a stop to restrict vertical depression of the handle, the two bushing parts being threadedly connected so that the length of the entire bushing unit is variable by rotation of the respective bushing parts thereby varying the distance which the handle may be depressed. Another known prior art device utilizes a cam unit having a sloping cam surface disposed to act as a stop for the handle, the cam unit being either rotatable or slidable to vary the effective height of the cam surface thereby regulating the distance which the handle may be depressed.